If the measure of an angle is $39°$, what is the measure of its complementary angle?

• A. $39°$
• B. $129°$
• C. $141°$
• D. $51°$

Answer: (D)

Verified step by step guidance

1. Recall that complementary angles are two angles whose measures add up to 90 degrees.
2. Let the measure of the given angle be \$39^\circ\( and the measure of its complementary angle be \)x$ degrees.
3. Set up the equation based on the definition of complementary angles: \$39^\circ + x = 90^\circ$.
4. Solve for \(x\) by subtracting \$39^\circ\( from both sides: \)x = 90^\circ - 39^\circ$.
5. Simplify the right side to find the measure of the complementary angle.